Locking key for outlet boxes



March 25, 1941 BETEBENNER 2,236,130

LOCKING KEY FOR OUTLET BOXES] Filed Sept. 15, 1959 SAW;

Patented Mar. 25, 1941 UNITED STATES PATENT OFFICE 1 Claim.

This invention relates to outlet boxes for electric conductors and more particularly to means for detachably securing the conduit clamping members in position on said outlet boxes.

The object of the invention is to provide an outlet box, the conduit clamping members of which are provided with annular seating grooves adapted to receive resilient locking keys or washers which keys firmly engage said clamping members and the inner walls of the outlet box, respectively, and serve to detachably hold the parts against accidental separation without the employment of the usual clamping nuts.

A further object of the invention is to provide a resilient locking key comprising a Ushaped body portion, the legs of which are adapted to straddle the grooved end of a conduit clamp, said legs being provided with intermediate resilient bowed portions and having their inner edges at said bowed portions deflected laterally to form concaved gripping members adapted to bite into the walls of the seating groove in the conduit clamp when the locking key is positioned thereon.

A still further object of the invention is generally to improve this class of devices so as to increase their utility, durability and efficiency.

In the accompanying drawing forming a part of this specification and in which similar numerals of reference indicate corresponding parts in all the figures of the drawing:

Figure 1 is a bottom plan view, partly in section, of an electrical outlet box provided with a resilient locking key constructed in accordance with the present invention,

Figure 2 is a front elevation of the locking key or washer detached,

Figure 3 is an edge view,

Figure 4 is a transverse sectional view taken on the line 4-4 of Figure 2, and

Figure 5 is a detail vertical sectional view, the locking key or Washer being shown in elevation.

The improved locking key or washer forming the subject-matter of the present invention is principally for use in connection with electrical outlet boxes, junction boxes and the like, and in Figure 1 of the drawing is shown applied to the outlet box of standard construction, in which 5 designates the body of the box and 6 openings formed in the opposite walls thereof to permit the insertion of an armored cable or other electric conduit, indicated at "I.

Fitted within. the openings 6 are clamping members 8 having their outer ends formed with spaced threaded ears 9 adapted to receive a screw or similar fastening device I0 so that, when the screw is tightened, the armored conduit '1 will be firmly clamped in position thereon. The clamping members are provided with annular stop shoulders II which bear against the adjacent outer walls of the outlet box 5, and projecting inwardly from the shoulders I I are cylindrical extensions I2 disposed within the box and provided with annular seating grooves I3 adapted to receive resilient locking keys or washers, indicated at M. The locking keys I4 are each preferably stamped or otherwise formed from a single sheet of resilient metal cut into substantially U-shape, as shown, to provide coacting legs I5 adapted to fit within the adjacent seating groove I3, as best shown in Figure 1 of the drawing.

The intermediate portions of the legs I5 are curved laterally to form resilient outwardly bowed portions I6, and the inner edges of the legs at said bowed portions are concaved or defiected laterally to form gripping edges I? adapted to bite into the wall of the adjacent seating groove and assist in preventing displacement of the locking key. The legs I5 between the bowed portions I B and the free ends of said legs are disposed in the same vertical plane to form flat smooth terminals I8 which-assist in guiding the key in position within the groove of the clamping member. The distance between the flat terminals I8 of the key is preferably less than the distance between the deflected edges I1 so that the flat terminals I8 will spring laterally when fitting the key within the sea-ting groove and after the key has been driven home the fiat terminals I8 will contract and prevent displacement of said key.

The closed ends of the locking keys are provided with laterally extending lips I9 to facilitate positioning the keys on the clamping members 8 and also to facilitate the removal of said keys when desired. Instead of forming the locking keys with the lips I9, each key may be provided with an opening for the reception of a nail, screw-driver or the like to facilitate placement and removal of the keys.

When using the device, the key is inserted Within the adjacent seating groove 6 with the concave side of the bowed portion I6 opposite the inner wall of the junction box. By then exerting an inward pressure on the lip I9, the flat terminals I8 will be forced apart, causing the legs of the key to straddle the extension I2 at the groove I3 therein and when the key reaches the limit of its inward movement, the inherent resilstructed will cause the fiat terminals l8 to spring inwardly so as to lock the key in position on the clamping member. As the key is forced to its seat within the groove, the deflected edges l7 thereof will bite into the walls of the groove and further assist in preventing accidental displacement of the key. In order to remove the key for the purpose of changing the armored conduits or efiecting any necessary repairs to the junction box, it is merely necessary to: exert a downward pressure on the lip I9 either with the finger or with a suitable tool when the fiat terminals l8 of the locking key will be forced outwardly and thus permit ready withdrawal of the key from its seating groove. The bowed portions l6 of the key not only impart the desired resiliency to the legs but also serve to reinforce and strengthen the same, while the laterally deflected lips I! further strengthen the key and provide a biting edge for engagement with the walls of the seating groove in the clamping member. By means of the improved resilient locking key or washer -iency of the material of which the key is com the clamping members of armored cables and other conduits may be detachably secured in position within the receiving openings of an outlet box without the employment of clamping nuts which usually engage the inner threaded terminals of said clamping members.

It will, of course, be understood that the locking keys may be made in different sizes and shapes and constructed of any suitable material without departing from the spirit of the invention.

Having thus described the invention, What is claimed as new is:

A resilient locking key for securing a conduit in an outlet box comprising a one-piece U-shaped body of resilient sheet metal, said body being outwardly bowed longitudinally thereof, and arms of the U-shaped body having portions along their inner edges bent outwardly to provide outstanding lips having longitudinally curved outer edges for gripping engagement in grooves in opposite side portions of the terminal of a conduit.

HARRY E. BETEBENNER. 

